Hi, I recently bought an Asus ROG STRIX B550-F GAMING MB with an AMD Ryzen 5 5500GT CPU (and installed the latest BIOS: 3607). I'm running Debian Testing/Sid on it with kernel 6.9 and now 6.10 and it seems to work great. I've been doing some (unrelated) tests with `rngtest` from the `rng-tools5` package and wondered how it would fare on my AMD CPU. And I found out it doesn't work at all! But on another system I have (Asus ROG CROSSHAIR VII HERO MB + AMD Ryzen 1800X CPU) it works absolutely fine. # dmesg | grep ccp [ 5.399853] ccp 0000:07:00.2: ccp: unable to access the device: you might be running a broken BIOS. [ 5.401031] ccp 0000:07:00.2: tee enabled [ 5.401113] ccp 0000:07:00.2: psp enabled Found an article [1] which could be relevant and downloaded and ran the accompanying test program (written by Jason Donenfeld): # ./amd-rdrand-bug Your RDRAND() does not have the AMD bug. # ./test-rdrand RDRAND() = 0x47c993c0 RDRAND() = 0xec7c697d ... (more seemingly random numbers) RDRAND() = 0xba858101 I tried it with the latest microcode dd 2024-07-10, but that didn't make a difference. So I'd like to know if this may actually be a bug on the kernel side. Happy to provide additional information or run tests or try patches. Cheers, Diederik [1] https://arstechnica.com/gadgets/2019/10/how-a-months-old-amd-microcode-bug-destroyed-my-weekend/
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